Description

Call the callback when a status change for process ID
pid
(or any
PID
if
pid
is
0
) has been received(a status change happens when the process terminates or
is killed, or, when
trace
is TRUE, additionally when it is stopped or continued). In other words,
when the process receives a
SIGCHLD
,
Ev
will fetch the outstanding exit/wait status for all changed/zombie children
and call the callback.

It is valid to install a child watcher after an
EvChild
has exited but before the event loop has started its next iteration. For
example, first one calls
fork
, then the new child process might exit, and only then an
EvChild
watcher is installed in the parent for the new
PID
.

You can access both exit/tracing status and
pid
by using the
rstatus
and
rpid
properties of the watcher object.

The number of
PID
watchers per
PID
is unlimited. All of them will be called.